(a) Technical Field
The present disclosure relates to a damper pulley for a crankshaft, more specifically, to a damper pulley for a crankshaft that is capable of preventing oil leakage and to a method for manufacturing the same.
(b) Description of the Related Art
As is well known in the art, internal combustion engines are used to drive automobiles and other vehicles. Typically, a reciprocating operation of cylinders in an internal combustion engine generates power that is transmitted to wheels of the vehicle through a crankshaft. The engine has a cylinder head including the cylinders, where a sequential explosion of gases in the cylinders drives the crankshaft.
The crankshaft translates reciprocating motion of pistons into rotational motion in a power stroke to transmit the output of the engine to the outside and transmits motion to the pistons in an intake stroke, a compression stroke, and an exhaust stroke.
The rotation and torque of the crankshaft causes unwanted vibrations. A damper pulley is mounted on one end (accessory drive) of the crankshaft to counter torsional and resonant vibrations from the crankshaft.
The damper pulley has a hub mounted on the one end of the crankshaft and a rim connected to the hub. An oil seal is mounted on an outer surface of the hub of the damper pulley. Accordingly, the oil seal is interposed between the cylinder block and the damper pulley to prevent oil leakage between the cylinder block and the damper pulley.
A damper pulley in the related art typically is made of cast iron with high wear resistance. However, the damper pulley has a disadvantage in that the weight of the damper pulley is excessive. To solve this problem, a damper pulley may be made of a light metal, i.e., a metal with a low density, such as aluminum, magnesium, or the like. The damper pulley made of the light metal has an advantage of being relatively light in weight.
However, since the damper pulley is made of the light metal, a hub of the damper pulley may be easily worn down due to contact with an oil seal, and thus oil may leak between the hub and the oil seal.
In recent years, a method of forming a coating layer on an outer surface of a hub by thermal spraying has been proposed, and such a coating layer may contribute to improving wear resistance of the hub.
However, the method using thermal spraying has shortcomings in that additional cost is incurred due to the addition of thermal spraying and post-processing of a coated surface by thermal spraying, and a problem of stabilizing the quality of the coated surface additionally may result.
Further, the coating layer formed by thermal spraying may have a high porosity, and therefore oil may severely leak between the hub and an oil seal.